49. Group Anagrams

iven an array of strings, group anagrams together.

Example:

Input: ["eat", "tea", "tan", "ate", "nat", "bat"],
Output:
[
  ["ate","eat","tea"],
  ["nat","tan"],
  ["bat"]
]

Note:

• All inputs will be in lowercase.
• The order of your output does not matter.

class Solution {
    public String change(String a) {
        char[] temp = a.toCharArray();
        Arrays.sort(temp);
        String s = String.valueOf(temp);
        return s;
    }
    public List<List<String>> groupAnagrams(String[] strs) {
        int k = 0;
        List<List<String>> ans = new ArrayList<>();
        int n = strs.length;
        Map<String, List<String>>map = new HashMap<>();
        for (int i = 0; i < n; ++i) {
            String temp = change(strs[i]);
            if (!map.containsKey(temp)){
                List<String> t = new ArrayList<>();
                ans.add(t);
                map.put(temp, t);
                map.get(temp).add(strs[i]);
            } else {
                map.get(temp).add(strs[i]);
            }
        }
        
        return ans;
    }
}